Multithreaded Programming Guide

Acquiring a Write Lock on a Read-Write Lock Before a Specified Absolute Time

The pthread_rwlock_timedwrlock(3C) function applies a write lock to the read-write lock referenced by rwlock as in the pthread_rwlock_wrlock() function, but attempts to apply the lock only until a specified absolute time.

pthread_rwlock_timedwrlock Syntax

#include <pthread.h>
#include <time.h>

int  pthread_rwlock_timedwrlock(pthread_rwlock_t   *restrict rwlock, 
     const struct timespec *restrict abs_timeout);

The calling thread acquires the write lock if no other reader thread or writer thread holds the read-write lock rwlock. If the lock cannot be acquired without waiting for other threads to unlock the lock, this wait will be terminated when the specified timeout expires. The timeout expires when the absolute time specified by abs_timeoutpasses, as measured by the CLOCK_REALTIME clock (that is, when the value of that clock equals or exceeds abs_timeout) or if the absolute time specified by abs_timeout has already been passed at the time of the call. The pthread_rwlock_reltimedwrlock_np() function is identical to the pthread_rwlock_timedwrlock() function, except that the timeout is specified as a relative time interval.

pthread_rwlock_timedwrlock Returns

If successful, returns 0 if the lock for writing on the read-write lock object referenced by rwlock is acquired. Otherwise, an error number is returned to indicate the error.



The lock could not be acquired before the specified timeout expired.



The calling thread already holds the rwlock.



The value specified by rwlock does not refer to an initialized read-write lock object, or the timeout nanosecond value is less than zero or greater than or equal to 1,000 million.